Aircraft energy storage mounting system

ABSTRACT

An aircraft includes a battery pack, an internal support structure to support the battery pack in the aircraft, a first bracket rigidly coupling the battery pack to the support structure, and a second bracket rotationally coupling the battery pack to the support structure. The first and second brackets may be located on opposite sides of the battery pack. The internal support structure may be located in a wing of the aircraft and the first and second brackets may be aligned in a fore-aft direction of the aircraft. The internal support structure may be located in a nacelle of the aircraft and the first and second brackets may be aligned along a transverse direction of the aircraft. The second bracket may include two hangers to support a mass of the battery pack in tension.

TECHNICAL FIELD

This invention relates generally to the aviation field, and morespecifically to a new and useful energy storage system in the aviationfield.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

To easily identify the discussion of any particular element or act, themost significant digit or digits in a reference number refer to thefigure number in which that element is first introduced.

FIG. 1 is a schematic view of an aircraft energy-storage systemaccording to one example.

FIG. 2 is a plan view of one example of the system of FIG. 1 , in whichthe system comprises a rotorcraft.

FIG. 3 is a rear perspective view of the rotorcraft of FIG. 2 .

FIG. 4A and FIG. 4B are front view and side view representations of therotorcraft of FIG. 2 .

FIG. 5 is a cross-sectional representation of a wing of the rotorcraftof FIG. 2 according to one example.

FIG. 6 is a cross-sectional representation of a wing of the rotorcraftof FIG. 2 according to one example.

FIG. 7 is a cross-sectional representation of a nacelle of therotorcraft of FIG. 2 , according to one example.

FIG. 8 is a cross-sectional representation of a nacelle of therotorcraft of FIG. 2 , according to one example.

FIG. 9 is a perspective view of a battery pack for use in the system ofFIG. 1 according to one example.

FIG. 10 is a perspective view of a battery pack for use in the system ofFIG. 1 according to another example.

FIG. 11 is a cutaway plan view of a wing of the rotorcraft of FIG. 2showing a battery pack mounted therein according to one example.

FIG. 12 is a perspective view of a battery module from the battery packof FIG. 11 according to one example.

FIG. 13 is a cutaway plan view of an example of a wing and nacelle ofthe rotorcraft of FIG. 2 showing battery packs mounted therein accordingto one example.

FIG. 14 is a perspective view of the battery module from the nacellebattery pack of FIG. 12 .

FIG. 15 is a cutaway perspective view of the wing and nacelle of FIG. 13.

FIG. 16 is a perspective view of a battery pack and associated mountingbrackets for use in the system of FIG. 1 according to another example.

FIG. 17A is a plan view of the right hand side mounting bracket of FIG.16 .

FIG. 17B is a perspective view of the mounting bracket of FIG. 17A.

FIG. 18 is a perspective view of part of a wing and nacelle for use inthe rotorcraft of FIG. 2 according to another example.

FIG. 19 is a cross-sectional view of the nacelle of FIG. 18 .

FIG. 20 is a perspective view of the vent shown in FIG. 19 .

FIG. 21 is a cross-sectional view of the wing of FIG. 18 .

FIG. 22A, FIG. 22B and FIG. 22C are schematic representations of a crosssection of a wing and an enclosed mass according to some examples.

FIG. 23A, FIG. 23B and FIG. 23C are a sequence of schematicrepresentations illustrating a method of inserting a battery pack into awing according to one example.

FIG. 24 is a schematic representation of battery loading apparatusaccording to one example.

DETAILED DESCRIPTION

The following description of examples of the invention is not intendedto limit the invention to these examples, but rather to enable anyperson skilled in the art to make and use this invention.

In one aspect, an aircraft includes a battery pack, an internal supportstructure to support the battery pack in the aircraft, and a bracket forcoupling the battery pack to the support structure, the bracketincluding a first connecting link rotationally coupled to the bracket ata first location and a second connecting link rotationally coupled tothe bracket at a second location, wherein the first connecting link isrotationally coupled to the battery pack at a third location and thesecond connecting link is coupled to the battery pack at a fourthlocation.

The bracket may be a first bracket that is coupled to a first side ofthe battery pack, and a second bracket may be rigidly coupled to anopposite side of the battery pack from the first side. The brackets maybe coupled to ribs of a wing of the aircraft.

The connecting links may be strip shaped and coupled to the bracket andthe battery pack at respective ends thereof. The connecting links may beoriented generally vertically. The rotational couplings may be bearings.At least one of the rotational couplings may be a ball joint.

The support structure may be located in a wing of the aircraft and aplane of the first and second brackets may be aligned with afore-and-aft direction of the aircraft. The support structure may belocated in a nacelle of the aircraft and a plane of the first and secondbrackets may be aligned perpendicular to a fore-and-aft direction of thenacelle.

The connecting links may be configured to bend when the brackets tiptoward or away from each other under bending of the wing.

In one aspect, an aircraft includes a battery pack, an internal supportstructure to support the battery pack in the aircraft, a first bracketrigidly coupling the battery pack to the support structure, and a secondbracket rotationally coupling the battery pack to the support structure.The first and second brackets may be located on opposite sides of thebattery pack.

The internal support structure may be located in a wing of the aircraftand the first and second brackets may be aligned in a fore-aft directionof the aircraft. The internal support structure may be located in anacelle of the aircraft and the first and second brackets may be alignedalong a transverse direction of the aircraft.

The second bracket may include at least one hanger to support a mass ofthe battery pack in tension. The at least one hanger may be coupled tothe bracket at an upper location of the hanger and to the battery packat a lower location of the hanger.

The aircraft may also include a first hanger coupled to the bracket at afirst location and a second hanger coupled to the bracket at a secondlocation, the first and second locations being horizontally spacedapart. The first and second hangers may rotationally coupled to thebracket and rotationally coupled to the battery pack.

The first and second hangers may be rotationally coupled to the bracketand to the battery using bearings. Other technical features may bereadily apparent to one skilled in the art from the following figures,descriptions, and claims.

FIG. 1 is a schematic view of an aircraft energy-storage system 100 inaccordance with one example. As shown, the system 100 includes one ormore battery packs 102. Each battery pack 102 may include one or morebattery modules 104, which in turn may comprise a number of cells 106.

Typically associated with a battery pack 102 are one or more propulsionsystems 108, a battery mate 110 for connecting it to the system 100, aburst membrane 112 as part of a venting system, a fluid circulationsystem 114 for cooling, and power electronics 116 for regulatingdelivery of electrical power (from the battery during operation and tothe battery during charging) and to provide integration of the batterypack 102 with the electronic infrastructure of the system 100. Asdiscussed in more detail below, the propulsion systems 108 may comprisea plurality of rotor assemblies.

The electronic infrastructure and the power electronics 116 canadditionally or alternately function to integrate the battery packs 102into the energy system of the aircraft. The electronic infrastructurecan include a Battery Management System (BMS), power electronics (HVarchitecture, power components, etc.), LV architecture (e.g., vehiclewire harness, data connections, etc.), and/or any other suitablecomponents. In a first variant, portions of the electronicinfrastructure are distributed within the battery (e.g., within amonolithic battery structure). In a second variant, portions of theelectronic infrastructure (e.g., power electronics) can be packagedseparately from the battery, which as within a dedicated enclosure.Packaging portions of the electronic infrastructure in dedicatedenclosures can enable power electronics to be line replaceable units(LRU) and/or can enable additional vibration isolation forvibration-sensitive electronics (e.g., HV power electronics). Theelectronic infrastructure can include inter-module electricalconnections, which can transmit power and/or data between battery packsand/or modules. Inter-modules can include bulkhead connections, busbars, wire harnessing, and/or any other suitable components.Inter-module electrical connections can be established before batterymounting, during battery mounting (e.g., automatically as a part of,included as part of the installation process), after mounting,synchronously with mounting, asynchronously with mounting, and/or withany suitable temporal relationship or dependence to the mountingprocess.

However, the electronic infrastructure can include any other suitablefeatures and/or can be otherwise suitably implemented.

The battery pack 102 functions to store electrochemical energy in arechargeable manner. The system 100 can include any suitable number ofbattery packs, such as 0, 1, 2, 3, 4, more than 4, and/or any othersuitable number of battery packs as a part of a complete energy system.Battery packs 102 can be arranged and/or distributed about the aircraftin any suitable manner. Preferably, battery packs are arranged proximalto a vertical lateral plane of the aircraft, but can be otherwisesuitably arranged. Battery packs can be arranged within wings (e.g.,inside of an airfoil cavity), inside nacelles, and/or in any othersuitable location on the aircraft. In a specific example, the systemincludes a first battery pack within an inboard portion of a left wingand a second battery pack within an inboard portion of a right wing. Ina second specific example, the system includes a first battery packwithin an inboard nacelle of a left wing and a second battery packwithin an inboard nacelle of a right wing. In a third example, one ormore battery packs 102 include a plurality of battery modules 104.

The battery pack 102 can include or exclude the battery packhousing/enclosures (e.g., closeouts), can be assembled into the aircraftseparately from the battery pack housing/enclosures, and/or can beotherwise suitably configured.

The battery pack 102 can include any suitable cells of any suitabletype, chemistry, voltage, maximum C-rate, capacity, and/or othercharacteristics. Battery cells 106 can be the same or different acrossvarious battery modules/packs, or within the same battery module/pack.Battery cell types (e.g., geometries) can include cylindrical, button,prismatic, pouch, and/or any other suitable cell geometries.

The battery pack 102 can include any suitable mounting and/or attachmentmechanism, which functions to mechanically couple the battery pack 102to the aircraft. The mounting mechanism can utilize any suitablefasteners, which can be include mechanical fasters such as:non-permanent fasteners, permanent fasteners, nuts, bolts, rivets,positive locking mechanisms, pins, clips, latches, snap-fit mechanisms,hook-and-loop, ties, and/or any other suitable mechanical fasteners. Themounting mechanism can additionally or alternately mount battery cells,modules, and/or packs with bonding agents, glue, cement, paste, epoxy,spray adhesives, thermosets, resins, tape, and/or any other suitableadhesives.

Battery packs 102 and/or battery modules 104 can be assembled into thewing/nacelle in any suitable manner as discussed in more detail below.Battery packs 102 and/or battery modules 104 are preferably insertedfrom below through an access hole, but can be inserted from any suitabledirection (inboard side, outboard side, top, front, rear, etc.). Batterypacks 102 or battery modules 104 can be raised vertically (e.g., frombelow), but additionally or alternately can be inserted at an angleand/or rotated into position. Angled insertion and rotating the batterypack 102 or battery module 104 into position can enable insertion evenif a dimension thereof exceeds a dimension of the access hole. In aspecific example, a chordwise dimension of the battery pack 102 orbattery module 104 can exceed a chordwise dimension of the access hole.In a second specific example, the chordwise dimension of the batterypack 102 or battery module 104 can be inserted at an angle aligned witha diagonal or space diagonal of the wing interior (whose length exceedsthe chordwise dimension of the battery pack 102 or battery module 104),and then the battery pack 102 or battery module 104 can be rotated intoplace such that a base-plane and/or chord of the battery pack 102 orbattery module 104 is substantially aligned with a wing chord. However,the battery pack 102 or battery module 104 can be inserted by: a jack(e.g., hydraulic, pneumatic, electric, manual), crane, user (e.g.,with/without assistive devices, etc.), and/or any other suitabledevice/process.

However, the system can include any other suitable batteries and/orbattery systems that can be otherwise suitably configured.

The system 100 can optionally include a cooling system (e.g. fluidcirculation system 114) that functions to circulate a working fluidwithin the battery pack 102 and/or battery module 104 to remove heatgenerated by the battery pack 102 and/or battery module 104 duringoperation or charging. The cooling system can optionally function tomitigate and/or reduce the likelihood of battery thermal events. Thecooling system can include one or more: fluid envelope, pumps, workingfluids, reservoirs, hoses, pipes, fluid couplings, valves, heatexchangers, refrigeration components, fans, ducts, pressure vents, caps,freeze plugs, fluid monitoring equipment (flow sensors, temperatureprobes, etc.), fasters, fluid seals, and/or any other appropriatecooling components. Cooling system components can be housed and/orpackaged with a battery pack, separately from batteries, withincavities, within the wing, within the nacelle, and/or in any otherappropriate location. In a specific example, the battery pack/module canbe connected to the fluid circulation system described in U.S.application Ser. No. 16/857,003, filed 23 Apr. 2020, which isincorporated in its entirety by this reference.

Battery cells 106, battery module 104 and/or battery packs 102 can befluidly connected by the cooling system in series and/or parallel in anysuitable manner. Modules can be connected by a set of inter-moduleconnections, which can run directly between two modules, connect viabulkhead connections (e.g., to ribs and/or spars), can be individuallyconnected to a common fluid connector (e.g., blind connector), and/orcan be otherwise suitably connected. Intra-module (or intra-pack)connections can be inside of heat sinks, built into the modulearchitecture (e.g., via a fluid manifold), and/or otherwise connected.On or more portions of the cooling system and/or components of thecooling system can be integrated into the construction of batterypacks/modules, mounted to battery packs/modules, and/or inserted withbattery packs/modules.

However, the system can include any other suitable cooling system (e.g.fluid circulation system 114), which can be otherwise suitablyimplemented.

FIG. 2 is a plan view of one example of the system 100 of FIG. 1 , inwhich the system 100 comprises a rotorcraft 200. The rotorcraft 200includes a fuselage 212, two wings 210, an empennage 208 and propulsionsystems 108 embodied as tiltable rotor assemblies 214 located innacelles 216. In the example shown in FIG. 2 , the battery packs 102comprise nacelle battery packs 204 and wing battery packs 206. In theillustrated example, the nacelle battery packs 204 are located ininboard nacelles 202, but of course it will be appreciated that thenacelle battery packs 204 could be located in other nacelles 216 formingpart of the rotorcraft 200. The rotorcraft 200 will typically includeassociated equipment such as an electronic infrastructure, controlsurfaces, a cooling system, landing gear and so forth. The rotorcraft200 is configured to enable wing or nacelle-mounted battery installationand operation.

The wings 210 function to generate lift to support the airborne aircraftduring forward flight. The wings 210 can additionally or alternatelyfunction to structurally support the battery packs 102, battery module104 and/or propulsion systems 108 under the influence of variousstructural stresses (e.g., aerodynamic forces, gravitational forces,propulsive forces, external point loads, distributed loads, and/or bodyforces, etc.). The wings 210 can have any suitable geometry and/orarrangement on the aircraft. As shown in FIG. 4A and FIG. 4B,preferably, the wings 210 are arranged above the passenger entrylocation (e.g., door), but can be arranged rearward of the passengerentry location, above a head clearance height in a ground configurationof the rotorcraft 200, and/or in any other suitable position. The wings210 can be anhedral, dihedral, straight, tapered toward a tip, gullwing, inverted gull wing, high-wing, mid-wing, low-wing, twisted, and/orhave any other suitable geometry.

The wings 210 can include spars that function as the primary spanwisestructural members of the wing. The spars can additionally oralternately function to connect the wing to the fuselage and/or functionto support all or a portion of the weight of the wings 210, propulsionsystems 108, and/or battery packs 102 when the aircraft is on theground. The wing can include any suitable number of spars. The wing caninclude 0, 1, 2, more than 2, and/or any other suitable number of spars.The spars can be arranged in any suitable manner within the wings 210.Preferably, the spars extend in a spanwise or lateral direction, and canextend across a full width of the aircraft, a partial width of theaircraft, terminate at the fuselage 212, extend through the fuselage212, and/or be otherwise suitably configured. Preferably, the wings 210includes spars on opposing ends of wing battery packs 206, but spars canbe arranged: forward of the wing battery pack 206, rearward of the wingbattery pack 206, above the wing battery pack 206, proximate a leadingedge of a wing 210, proximate a trailing edge of the wing 210, and/or inany other suitable configuration. However, spars can include any othersuitable features and/or be otherwise suitably implemented.

The wings 210 can include ribs that function to support portions of thewing skin and/or define the cross-sectional shape of the wing skin. Theribs can additionally or alternately function to mount one or morebattery packs/modules (or a portion of battery pack/module components)within the wing 210. The ribs are preferably mounted to the spars, andcan be solid, hollow, pocketed, truss-shaped, and/or have any othersuitable structure. The ribs can define any suitable cross-sectionalgeometry, and preferably define airfoil cross sections that, wheninterpolated, can form the wing exterior geometry. The ribs can definean inboard airfoil cross section (e.g., inboard of the wing battery pack206) and an outboard airfoil cross section (e.g., outboard of the wingbattery pack 206), however, the ribs can be otherwise configured tosupport a stressed skin wing (e.g., at an inboard and outboard portion)without defining the shape. The ribs can include any suitable materialconstruction such as: metal (e.g., aluminum, titanium, steel), composite(e.g., carbon fiber, fiberglass, etc.), plastic, and/or any otherappropriate material(s). The ribs can be bonded, fastened, welded,and/or otherwise suitably connected to the spars. However, ribs caninclude any other suitable features and/or be otherwise suitablyimplemented.

The wing 210 and/or ribs can include any suitable set of airfoil crosssections. Each cross section preferably defines a chord-line extendingfrom a leading edge to a trailing edge of the airfoil. The inboard andoutboard airfoil cross sections airfoil cross sections can cooperativelydefine: a twist angle, a dihedral (or anhedral) angle, taper, forward(or rearward) sweep angle, and/or any other appropriate geometriccharacteristics of the wing 210. The twist angle is preferably thedifference in the angle of attack of the chord angle of the inboardairfoil cross section and the outboard airfoil cross sections, and canbe positive, negative, 0, and/or any other appropriate twist angle. Thetwist angle (e.g., absolute value, positive, negative) can be between 0and 15 degrees, any suitable range therein, and/or any other suitableangle. The dihedral (or anhedral) angle is preferably defined by theangle, relative to the ground, of the line extending between thecenter-points (e.g., geometric, CoL) of the airfoil cross sections,projected into a frontal plane (or lateral/vertical plane). The dihedral(or anhedral) angle can be 0-30 deg, any suitable range therein, and/orany other appropriate anhedral/dihedral angle. The airfoilcross-sections can define any suitable taper in a spanwise direction,which is preferably defined in terms of a change in chord length and/orother cross sectional parameters (shape, area, thickness, chord length,etc.). The wing 210 is preferably a straight wing (rib cross sectionalarea does not vary), but can have a change in chord length and/or crosssectional area between the inboard and outboard airfoil cross sectionsof 5%, 10%, 20%, 30%, 50%, any range bounded by the aforementionedvalues, and/or any other suitable taper. The cross-sectional shape ofthe wing 210 can define any suitable thickness, which can have anysuitable relationship to the chord length. The thickness of the wing 210can be above a threshold percentage of the chord length, below athreshold percentage of the chord length, greater than the thickness ofthe battery, and/or have any other suitable thickness, such as <5%, 5%,10%, 12%, 15%, 20%, 21.5%, 23%, 25%, 30%, 35%, 50%, >50%, any rangebounded by the aforementioned values, and/or any other suitablethickness relative to the chord length. The wing thickness can bedefined, for each spanwise point, as: the maximum thickness, the minimalthickness of the airfoil cross-section that is between wing spars, theminimal thickness for chordwise positions of a retained mass (e.g.,battery pack) within the airfoil, and/or can be otherwise suitablydefined.

The wings 210 (and/or components thereof, such as the nacelles 216) caninclude a skin that functions to provide all or a portion of theexterior aerodynamic profile of the wing. The skin can additionally oralternately function to carry a portion of flight and/or ground loads ofthe aircraft (e.g., stressed skin wing), and/or define the wing shape.The skin can additionally function to mount one or more battery packs102 or battery modules 104 to the wing 210. The skin preferably includesan upper surface opposing a lower surface, with the upper and lowersurfaces intersecting along a leading edge and a trailing edge of thewing. The skin geometry is preferably smooth and interpolated across theairfoil cross sections of the wing. Preferably, the lower surface of theskin is relatively flat along an inboard portion of the wing 210 and/oracross a span of the wing battery pack 206, however the lower surfacecan be concave, convex, or have any suitable geometry. Specifically, forcross sectional chord length (L), the lower surface of the skinpreferably deviates from the chord line (for each cross section) by lessthan a threshold distance, which can be: 0.02L, 0.05L, 0.07L, 0.1L,0.15L, 0.2L, 0.25L, and/or any other suitable threshold. The lower skinsurface can induce (or be assumed to induce) turbulent flow, promotelaminar flow, and/or induce other flow patterns during wing operation,which can assist with wing geometry optimization. At the root (inboardsection) of the wing 210, the relatively flat geometry can be proximalto a door, provide clearance for a door in an open configuration,provide headroom for uses standing adjacent to a door (outboard relativeto the door), provide clearance for a user standing below the wing(e.g., 6′ ground clearance, 6′6″ ground clearance, 7′ ground clearance,8′ ground clearance, etc.) in a ground configuration, and/or otherwisesuitably improve user access to the aircraft.

The skin can include any suitable material construction such as: metal(e.g., aluminum, titanium, steel), composite (e.g., carbon fiber,fiberglass, etc.), plastic, and/or any other appropriate material(s).The skin can be bonded, fastened, welded, and/or otherwise suitablyconnected to the spars and/or ribs.

However, skin can include any other suitable features and/or beotherwise suitably implemented.

FIG. 3 is a translucent perspective view of the rotorcraft 200 of FIG. 2. FIG. 3 illustrates the positioning of the wing battery packs 206 inthe wings 210 as well as the positioning of the nacelle battery packs204 in the inboard nacelles 202.

FIG. 4A and FIG. 4B are front view and side view representations of therotorcraft 200 of FIG. 2 , illustrating the positioning of thepropulsion systems rotor assemblies 214 above passenger head height whenthe rotorcraft 200 is parked.

FIG. 5 and FIG. 6 show cross-sectional representations of a wing 210 ofthe rotorcraft 200 of FIG. 2 , in accordance with one example. Asillustrated the wing 210 can include a cavity 502 that functions tohouse and/or retain a retained mass, such as battery pack 504 in oneexample. The cavity 502 is preferably optimized to maximize an availableinternal volume in the wing (and/or nacelle), while still enablingefficient wing operation (e.g., efficient lift generation, withoutexceeding a threshold coefficient of drag in forward flight, withoutexceeding a threshold CL/CD value, etc.).

The cavity 502 can be located in any suitable portion of the wing 210.The cavity 502 can be: located on an inboard portion of the wing 210,between an inboard rib (not shown) and an outboard rib 510, between aforward spar 508 and a rearward spar 506, inboard of a nacelle 216,outboard of a nacelle 216, inside a nacelle 216, and/or be otherwisesuitably located within the wing 210. The cavity 502 has dimensions thatare at least as large as the battery pack 504 (e.g., with a nominalclearance, with no clearance), but can alternately house the batterypack with an interference fit, and/or otherwise suitably house thebattery pack 504.

In this example, a mounting mechanism or structure, described in moredetail below, can connect a monolithic battery structure (e.g. batterypack 504) to the wing airframe (e.g., ribs, spars, and/or skin). Themonolithic battery structure can form a portion of the wing skinextending across an access hole. The monolithic battery structure can becompleted before mounting/installation, or can be completed uponinstallation. In a specific example, the monolithic battery structure iselectrically complete upon installation/mounting and defines a nominalpack voltage of operation. This nominal pack voltage can be an operatingvoltage of one or more electrical systems of the aircraft, and themonolithic battery structure can be connected in series and/or parallelas an element of the aircraft energy system.

The battery cells 106 and/or battery modules 104 can cooperativelydefine any suitable cross sectional geometries. Preferably, the crosssectional geometry of the battery cells 106 and/or battery modules 104is rectangular, but can alternately be trapezoidal, include chamferedcorners (e.g., on upper corners), and/or include any other appropriategeometry. Alternately, the battery cells 106 and/or battery modules 104can define a circumscribed rectangular cross section. The battery cells106 and/or battery modules 104 cross sections can cooperatively define alower battery base plane defining a width and length of the battery pack102. Preferably, the cross sections of the battery cells 106 and/orbattery modules 104 are invariant (or substantially invariant) in aspanwise direction of the wing, but can alternately be variable, includedistinct segments (e.g., each invariant), and/or be otherwise suitablyimplemented. The cross-sectional geometry of the battery cells 106and/or battery modules 104 can be the same for a battery pack 504mounted within an inboard portion of the wing as for a battery mountedwithin a nacelle, or can be different

The rotorcraft 200 can include a cover 512 that functions to separatethe battery cells 106 within the cavity 502 from a remainder of the winginterior. Covers 512 can additionally or alternately function toincrease the structural rigidity of the wing in torsion and/or bending,and/or function as a closeout. The cover 512, alone or in conjunctionwith other closeouts, can provide ingress protection to the battery(e.g., IP65, IP66, IP67, etc.), fluidly isolate the battery, and/orprovide a fire-resistant barrier between the battery and otherstructural elements of the wing (e.g., spars, ribs, skin, etc.). Thecover 512 and/or other closeouts can prevent ingress of dust, solidobjects, water droplets, water jets, human fingers, and/or any otherundesirable objects. The cover 512 can be mounted to the ribs, uppersurface of the skin, spars, the battery pack, baseplate, and/or othersuitable components/endpoints. The cover 512 can optionally include apinned or rigid connection to the battery pack 504 (e.g., top of thebattery pack, side of battery opposing the baseplate) and/or batterycells 106, which can increase the resilience of the energy system tovibrational modes. However, the cover can include any other suitablefeatures and/or be otherwise suitably implemented.

The rotorcraft 200 can optionally include a baseplate adaptor 514 thatfunctions to couple the base plane of the retained mass (e.g. thebattery pack 504) to a baseplate 516. The baseplate adaptor 514 canadditionally or alternately structurally support the mass retained bythe baseplate. Twisting, tapering, or other cross sectional variationsof the wing skin across the span of the battery pack 504 can result in agap (or offset) between a base plane of the battery pack 504 and thebaseplate 516 or the wing skin. The baseplate adaptor 514 can partiallyor fully occupy or account for this offset. The baseplate adaptor 514can be fastened to the baseplate 516 and the battery pack 504 in anysuitable manner.

The baseplate adaptor 514 can preferably be attached by an adhesive,bonding agent, or mechanical fastener, but can alternately be formed asa part of the baseplate and/or separately connected to the batterycells, battery modules, ribs, spars, and/or skin of the aircraft. Thebaseplate adaptor can include any suitable geometry. The baseplateadaptor 514 can span a full breadth (spanwise and/or chordwisedirection) of the baseplate 516 and/or the battery pack 504, or can spanonly a portion of the baseplate 516 and/or the battery pack 504 breadth.

The baseplate adaptor 514 can be a singular component (e.g., per batterypack, per battery module 104) or can include a plurality of distributedcomponents (e.g., analogous to rib supports). The baseplate adaptor 514can be rigid, semi-compliant, or compliant. Baseplate adaptor 514rigidity can improve load transmission, vibration characteristics (e.g.,damping), mounting tolerances, and/or provide increased structuralintegrity. However, the baseplate adaptor 514 can include any othersuitable features and/or be otherwise suitably implemented. The massretained within the wing by the baseplate 516 and/or baseplate adaptor514 can include: battery mass, fluid (e.g., liquid hydrogen) mass, fuelmass, fuel cell mass, fluid circulation system mass, cooling componentmass, and/or any other suitable mass.

The battery pack 102/504 functions to store electrochemical energy in arechargeable manner. The battery pack 102, which is preferably at leastpartly isolated from loads experienced by the rotorcraft 200, canadditionally or alternately function to increase the structural rigidityof the wing 210 in torsion and/or bending. The system can include anysuitable number of battery packs 102, such as 0, 1, 2, 3, 4, more than4, and/or any other suitable number of battery packs 102 as a part of acomplete energy system. Battery packs 102 can be arranged and/ordistributed about the aircraft in any suitable manner. Preferably,battery packs are evenly distributed about the aircraft CoG and/or CoL,such as with an even number on the left/right sides and/orforward/rearward sides of the aircraft CoG or CoL, but can be unevenlydistributed and/or otherwise arranged. Preferably, battery packs 102 arearranged proximal to a vertical lateral plane of the aircraft, but canbe otherwise suitably arranged. Battery packs 102 can be arranged withinwings (e.g., inside of a cavity), inside nacelles, and/or in any othersuitable location on the aircraft. In a specific example, the systemincludes a first battery pack 504 within an inboard portion of a leftwing and a second battery pack 504 within an inboard portion of a rightwing. In a second specific example, the system includes a first nacellebattery pack 204 within an inboard nacelle 202 of a left wing 210 and asecond nacelle battery pack 204 within an inboard nacelle 202 of a rightwing 210. In a third example, one or more battery packs include aplurality of battery modules.

The battery packs 102 can individually or cooperatively have anysuitable weight relative to the aircraft (loaded and/or unloaded). Thebattery weight can be less than 10%, 10%, 20%, 30%, 40%, 50%, any rangebounded by the aforementioned values, and/or any other suitable weightrelative to the aircraft. The battery pack weight can be: less than 5lbs, 5 lbs, 50 lbs, 100 lbs, 250 lbs, 300 lbs, 350 lbs, 400 lbs, 500lbs, 1250 lbs, 1500 lbs, greater than 1500 lbs, any range bounded by theaforementioned values, and/or any other suitable weight.

The battery packs 102 can include or exclude a battery packhousing/enclosures (e.g., closeouts), can be assembled into the aircraftseparately from the battery pack housing/enclosures, and/or can beotherwise suitably configured.

The wing can include an access hole 518 (see further FIG. 22C), whichfunctions to enable insertion of the battery pack 504 into the wing 210therethrough. The access hole 518 can be proximal to the cavity 502,define a boundary of the cavity 502, be continuous with the cavity 502,fluidly connect the cavity (e.g., bottom, top, side, portion thereof,interior) with the exterior of the wing 210, and/or have any othersuitable relationship to the cavity 502. The access hole 518 ispreferably defined by the wing skin 520, but can alternately be definedby an associated closeout and/or any other suitable reference. Theaccess hole 518 can be located on any suitable portion of the wing210—it can be arranged on an inboard portion, root portion, outboardportion, upper surface, lower surface, nacelle inner side, nacelle top,nacelle outer side, nacelle bottom, aligned with the cavity (e.g.,projection onto the wing skin), offset from the cavity, and/or any othersuitable location.

In variants, the access hole 518 is arranged on the high-pressure sideof the wing (e.g., lower surface) since it can be advantageous to placeaerodynamic disturbances on high pressure side of wing 210 so that lowpressure (higher velocity) flow is as uninterrupted as possible—whichcan minimize efficiency impacts and/or CL impacts of surface features(when compared to the effect of the same surface features incident onthe low pressure side). The wing skin 520 and/or aerodynamic profile ofthe wing 210 can be aerodynamically optimized for prescribed initiationof laminar to turbulent boundary layer flow at an access hole portion ofthe lower surface (e.g., leading edge of the access hole 518, trailingedge of the access hole 518, across a width of the access hole 518,etc.). Alternately, the wing can be optimized for laminar to turbulenttransition of boundary layer across an opposite surface of the wingrelative to the access hole 518, or another portion of the same surfaceof the wing 210 relative to the access hole during a portion/all modesof flight and/or attack angles. Alternately, there can be no prescribedboundary layer characteristics, and/or the wing 210 can be otherwiseimplemented.

The access hole 518 can define any suitable geometric parameters. A(chordwise) length can be defined for the access hole relative to achord length (L) of the wing 210. The length is preferably between 0.3Land 0.8L, but can be any suitable length in absolute or relative terms.A (spanwise) breadth can be defined for the access hole 518 relative toany suitable components. The breadth can be substantially the distancebetween an inboard and an outboard rib. In a first variation, the accesshole breadth extends between two ribs, with no intervening ribs. In asecond variation, the access hole breadth spans one or more ribs. In aspecific example, the battery pack 102 includes a number (N) modules,and the number of intervening ribs on the access hole breadth is relatedto the number of modules: there can be N−1 ribs, N+1 ribs, and/or anyother suitable number of ribs spanned by the access hole 518. The accesshole breadth can extend from an inboard portion of the wing 210 up to aspanwise location of a nacelle, terminate before a nacelle, extendacross a portion of a nacelle, extend across a portion of the wing 210outboard of a nacelle, and/or be otherwise suitably configured.

In a specific example, an access hole 518 can be located on the lowersurface of the wing. In a second specific example, an access hole can belocated on a nacelle (e.g., lower surface, upper surface, outboardsurface, inboard surface, etc.), and/or configured to minimize a dragprofile of the nacelle. However, the access hole 518 can include anyother suitable features and/or be otherwise suitably implemented.

The wing 210 can include a closeout that functions to enclose and/orprotect a battery pack and/or battery module from surroundings.Closeouts can cover, mount to, and/or be otherwise associated withaccess holes 518, but can alternately be internal inside the wing.Closeouts can mount directly to the battery pack 504, directly to thewing 210, be manufactured as a part of the wing 210, and/or be otherwisemounted/assembled into place. Closeouts can be attached: prior tobattery pack 102 or battery module 104 insertion, synchronously or as apart of battery insertion, independently of the batteries, and/or beotherwise suitably attached. Closeouts can be manufactured from anysuitable materials.

Preferably, closeouts include the same material composition as the wingskin, but can alternately include a different material composition fromthe wing skin. Materials can include: fire-resistant materials, metals(e.g., aluminum, steel) and/or other materials, with any suitablecoatings, finishes, heat treatments, and/or other suitable materials.The material can include: carbon fiber, titanium, aluminum, fiberglass,and/or any other suitable metal, composite, or other material. Thecloseout can be mechanically connected to the wing (and/or nacelle) bymechanical fasteners, adhesives/bonding agents, and/or otherwisesuitably connected. Mechanical fasteners can be inserted and/or appliedfrom below the wing and/or normal to the wing skin, with fastener headsflush with the wing skin—which can minimize the aerodynamic influence ofexternal fasteners. Closeouts can include any suitable seals (e.g.,fluid seals) in conjunction with attachment mechanisms. Closeouts caninclude any suitable mechanical tolerances, clearances, and/or otherfeatures to simplify manufacturing and/or assembly.

Closeouts can include a baseplate 516 that functions to enclose, cover,and/or shroud an access hole. The baseplate 516 can additionally oralternately function to structurally support a portion of the wing 210and/or stiffen the wing 210 (e.g., in torsion). By closing the accesshole 518 in the wing skin 520, the baseplate can distribute torsional(and bending) loads across the wing skin 520, reducing the stressconcentrations that would otherwise arise from the access hole. In aspecific example, airfoil torsion and/or other loads are transmittedalong the wing skin 520 and through the closeout. In this example, morethan a threshold proportion of the airfoil loads (e.g., generated duringforward and/or vertical flight) are routed around the cavity 502interior (e.g., 100%, 90%, 80%, etc.). Additionally, the baseplate 516can match or approximate the missing airfoil geometry of the wing skin520 (interpolated between ribs, etc.), thereby minimizing theaerodynamic influence of the access hole 518. In a first variant,battery cells 106, battery module 104 or a battery pack 102 can bemounted to the baseplate 516 prior to battery insertion. In a secondvariant, battery cells 106, battery module 104 or a battery pack 102 canbe mounted to the wing independently of the baseplate. In the first andsecond variants, the baseplate 516 can avoid structural loads from beingtransferred to the cells 106 (stressing the cells 106), which couldresult in cell life degradation and/or failure. A baseplate 516 cancloseout an access hole 518 in the wing skin 520 on any suitable portionand/or component of the wing including: an inboard portion of the wing,a nacelle, and/or any other suitable component/location. However, thebaseplate 516 can include any other suitable features and/or beotherwise suitably implemented.

Also as shown in FIG. 6 , a spar (such as rearward spar 506) may beprovided with a burst membrane 112 forming part of a vent pathway 602 aspart of a venting systems. Venting systems are discussed in more detailbelow.

The rotorcraft 200 can optionally include control surfaces 522, whichfunction to improve control authority in one or more modes of flight bychanging the aerodynamic profile of the aircraft. Control surfaces canoptionally function to provide vent pathways 602 out of the winginterior, forming an end of a vent and/or selectively opening andclosing a vent relative to the aircraft exterior. Control surfaces caninclude: flaps, air brakes, ailerons, slats, elevators, spoilers,rudders, ruddervators, and/or any other suitable control surfaces. Invariants, the control surfaces can be redundantly powered and/orcontrolled. In a specific example, the control surfaces are redundantlypowered by the battery architecture as described in U.S. applicationSer. No. 16/428,794, filed May 31, 2019, which is incorporated in itsentirety by this reference. However, the system 100 can include anyother suitable control surfaces that can be otherwise suitablyconfigured.

FIG. 7 and FIG. 8 show cross-sectional representations of an inboardnacelle 202 of the rotorcraft 200 of FIG. 2 , in accordance with oneexample. As can be seen from FIG. 7 a cavity 702 is provided in theinboard nacelle 202 into which a battery pack 704 can be inserted via anaccess hole 706, which is closed by cover 708 that completes the outersurface of the inboard nacelle 202. The inboard nacelle 202 alsoincludes vents 710 and burst membranes 112, which are discussed in moredetail below.

The system 100, of which rotorcraft 200 is an example, can optionallyinclude a venting system that functions selectively to fluidly connectone or more battery modules 104 or battery packs 102 to the aircraftsurroundings (e.g., the ambient environment). The venting systemadditionally or alternately functions to divert any discharge away fromprimary aircraft structures during a thermal event involving a batterypack 102 or battery module 104.

As illustrated in FIG. 8 , the venting system can include one or morevents 804 that fluidly connect one or more battery cells in a batterypack 704 with the ambient environment. Each vent 804 can include one ormore burst membranes 112 and define one or more vent pathways 802. Thevent 804 and/or vent pathway 802 may fluidly and/or mechanically connectto one or more batteries (e.g., battery interior, battery cell vent,pack, module, etc.). The vent 804 can include thermal insulation and/orfire-resistant materials, or may not include thermal insulation. Thevents 804 can be formed with portions of existing fire-enclosures,airframe components (wing skin, ribs, spars, etc.), control surfaces,and/or other suitable components.

While the vents illustrated herein are typically shown to have a singleinlet and outlet, the vents may also be formed as manifold vents, withmultiple inlets (e.g. from more than one battery module or battery pack)or with multiple outlets, or some combination thereof.

The burst membranes 112 function to selectively connect one or morebattery cells to an aircraft exterior in response to a thermal event. Aburst membrane 112 can include: a rupture disk, pressure safety disc,burst disc, burst diaphragm, pressure relief valve, and/or any othersuitable component. Each burst membrane 112 can be associated with oneor more of: a battery pack, a battery module, a spar, a rib (e.g.,spanned by the battery pack), a closeout, a wing, a vent path, a vent,the nacelle side (inboard/outboard), the fuselage side, and/or any othersuitable unit. Similarly, each unit (such as a: battery pack, batterymodule, spar, rib, closeout, wing, vent path, vent, nacelle side, etc.)can be associated with one or more burst membranes 112. Burst membranes112 can be arranged at one or more locations within a vent pathway 802and/or vent 804, such as: proximal to battery cells, proximal to theambient environment, at an aircraft exterior (e.g., forming part of wingskin and/or wing exterior), and/or in any other suitable location.

The burst membranes 112 can include any suitable geometry. A burstmembrane 112 can be a disc, oval, panel (e.g., rectangular), and/or haveany other suitable geometry, which encloses/covers any suitable area.The burst membrane 112 can be single directional or bi-directional,multi-use or single use (e.g., bursts and needs to be replaced), singlemembrane or multi-membrane (e.g., forward-acting and reverse buckling),and/or any other suitable membrane. The burst membrane 112 can beconstructed of and/or include any suitable materials, such as carbonsteel, Hastelloy, stainless steel, graphite, polymers, low-temperaturematerials (e.g., will deform and/or fail at temperatures above a bursttemperature/pressure), high temperature materials (e.g., will not deformand/or fail at temperatures/pressures), and/or any other appropriatematerials.

The burst membranes 112 can engage and/or release under any suitablepressure and/or temperature conditions. In a specific example, the burstmembranes 112 are configured to vent in excess of a pressure threshold(e.g., burst pressure) and/or temperature threshold, wherein the burstpressure is selected to activate in response to a thermal event, but notunder normal aircraft operating conditions.

The venting system is preferably operable between a sealed mode and aventing mode. In the sealed mode, the burst membrane 112 and/or vent 804fluidly separates a first region from a second region (i.e., enabling apressure differential therebetween). The sealed mode can preventparticulates and/or gasses from propagating from the second region tothe first region and vice versa. Alternately, the first and secondregions can be fluidly connected by a circuitous fluid pathway (e.g.,adjacent to fire sensitive structural components, passing through aparticulate and/or gas filter, etc.). In a venting mode, the ventingsystem fluidly connects the first fluid region to the second fluidregion (e.g., by a direct fluid path). In a specific example, the firstregion includes a battery cell 106 (e.g., inside the battery pack 704)and the second region includes an aircraft exterior. In a secondexample, the first region is an interior of a battery pack 102 and thesecond region is an exterior of the battery pack 102. In a thirdexample, the first region is a wing interior forward of a spar and thesecond region is a wing interior rearward of a spar. However, theventing system and/or vent can include any other suitable burstmembranes.

The vent and/or burst membrane can define one or more vent pathways withany suitable directionality. Vent pathways (e.g. vent pathway 602 orvent pathway 802) can be directed: away from the fuselage (outboard) tothe sides (e.g., of a nacelle), rearward, upward, downward, into aregion of an airfoil (or wing skin) configured to promote turbulentflow, into a region of an airfoil (or wing skin) configured to promotelaminar flow, out of a wing (single-directional or bi-directional),and/or have any other suitable directionality.

Battery venting pathways can be provided in an airfoil section of thewing 210 and/or nacelles (e.g. inboard nacelles 202) with any suitablearrangement. Venting pathways can extend through, between, away from,and/or around: spars, ribs, the wing skin, control surfaces, ribs,fire-resistant barriers, closeouts, and/or any other suitablecomponents. In a first variant, battery modules and/or cells can share acommon vent pathway extending through a spar and/or control surface(e.g., wing flap). In a second variant, battery modules and/or cells caninclude individual vent paths.

Vent pathways can be provided with any suitable relationship to thenacelles, e.g. inboard nacelles 202. Vent pathways can extend through anacelle side, top, bottom, and/or rear, can converge with a vent path inan airfoil section of the wing, and/or can be otherwise suitablyimplemented. The termination of vent pathways at the aircraft exteriorcan be inset within a persistent external cavity (e.g., aerodynamicallyoptimized) which can be selectively sealed, can form a portion of theexterior wing skin, and/or can be otherwise suitably configured.

The venting system can optionally include a safety relief valve (e.g.,pressure relief valve) that can be in series (e.g., before or after) orin parallel with one or more burst membranes 112. Safety relief valvescan be mounted and/or installed with the battery pack 102 or a batterymodule 104, but can alternately be a separate installation. In variants,the safety relief valve can be an LRU, which can be replaced with thebattery pack 102 or battery module 104 mounted in place and/or requireremoval of same, but can otherwise be built into the airframe/wing andthus separately replaceable. In variants, the safety relief valve canprevent undesired activation and/or rupture of the burst membrane when athermal event is not occurring. However, a safety relief valve can beotherwise suitably implemented in conjunction with the burst membraneand/or venting system. However, the venting system can be otherwisesuitably implemented and can include any other suitable componentsand/or features.

FIG. 9 and FIG. 10 respectively show perspective views of a battery pack900 and a battery pack 1000 for use in a system 100 in some examples.Battery pack 900 and battery pack 1000 can optionally include a batterymate 902 or battery mate 1002 respectively that function to couple abattery pack to a remainder of the energy system. The battery matepreferably includes a battery-side connector and a vehicle-sideconnector (e.g., corresponding male and female connectors).

The battery-side connector can be arranged on the top face, bottom face,broad face, narrow face, spanwise face, chordwise face, inboard face,outboard face, front face, back face, and/or any other suitable side,face, and/or vertex of the battery pack 900 or battery pack 1000. Thebattery-side connector can be arranged on a single battery module 104(e.g., on the end of the pack) and/or distributed between multiplebattery modules 104, shared/split between a battery pack 1000 mountedwithin an airfoil cross section and a nacelle mounted battery pack 900,and/or otherwise suitably configured. The battery-side connector can bewithin one or more battery enclosures and/or arranged an exterior of thebattery pack 900 or battery pack 1000.

The vehicle-side connector (e.g., a snorkel connector) can be sealedrelative to the aircraft environment in any suitable manner. The vehicleside connector can include: a fluid seal (e.g., sealed from the vehicleand/or ambient environment), electrical protections (e.g., insulation),thermal protections (e.g., thermal insulation, fire-resistant materials,etc.), vibration protections, EMI shielding, ingress protections, and/orany other suitable protections. Preferably, the vehicle-side connectoris arranged to minimize the wiring and/or tubing length onboard, and canbe arranged on the inboard side, outboard side, top, bottom, and/or inany other suitable location relative to the battery pack.

The battery mate 902 or battery mate 1002 can be aligned in any suitablemanner. The battery mate can be: self-aligning—allowing and/orcorrecting misalignment within a threshold (e.g., 1 mm, 5 mm, 1 cm,etc.; including a spring or other compliance mechanism; etc.), alignedby external features, manually aligned, and/or otherwise suitablyaligned.

The battery mate 902 or battery mate 1002 can include a fasteningmechanism, which functions to secure and/or retain the battery-side tothe vehicle side. The fastening mechanisms can be configured toindependently, synchronously, and/or simultaneously connect thebattery-side connector to the vehicle side connector. The fasteningmechanism can be automatic (e.g., engaged upon battery insertion and/ormounting), manual, and/or otherwise configured. Preferably, thefastening mechanism allows assembly without the use of additional tools(e.g., beyond devices used to lift and/or fasten the battery),soldering, crimping, waterproofing (e.g., application of locking fluidsor Teflon tape), but can be configured to assemble with suchinstruments. The fastening mechanism preferably connects via a linearmotion (e.g., same direction as insertion, orthogonal to insertiondirection), such as with snap-fit connections, jacks, plugs, push-pull,sliding connectors, and/or any other linear motion connectors.

Additionally or alternately, the battery mate 902 or battery mate 1002can connect via a rotational motion such as a screw locking mechanism,bayonet connector, and/or any other suitable rotation locking mechanism.Alternately, the battery mate 902 or battery mate 1002 can include nolocking mechanism directly retaining the vehicle-side connector relativeto the battery-side connector, and instead can rely on the mechanicalfastening of the battery and/or fixed position of the vehicle siderelative to the battery sides (e.g., monolithic battery and battery-sideconnector are fixed relative to the airframe and the vehicle-sideconnector is fixed relative to the airframe). In variants, thebattery-side and/or vehicle-side connectors can float (e.g., semi-rigid,non-rigid, adjust, etc.) relative to the battery mounting and/or otherrigid aircraft components, which can enable a user (or assistivedevices) to easily engage the battery mate 902 or battery mate 1002during assembly.

In variants, the fastening mechanism and/or alignment of the batterymate can allow engagement of the mate without a visual line of sight tothe vehicle-side connector, battery side connector, and/or battery pack.In a specific example, the battery mate includes blind mate connectors.However, the battery mate can include any other suitable features and/orcan be otherwise suitably implemented.

FIG. 11 is a cutaway plan view of an example of a wing 1100 of therotorcraft 200 showing battery packs 1102 mounted therein. In thisexample, the battery pack 1102 is mounted to the wing ribs 1104. Aninstalled battery pack 1102 defines a battery pack span, which is thetotal dimension of the battery pack 1102 in a left to right direction inFIG. 11 . The battery pack span can extend between two ribs, with nointervening ribs, or the battery pack 1102 can span one or moreintervening ribs 1104 as shown in FIG. 10 . In a specific example, thebattery pack 1102 includes a number (N) battery modules 1110, and thenumber of intervening ribs on the access hole breadth is proportional tothe number of modules: there can be N−1 ribs, N+1 ribs, and/or any othersuitable number of ribs 1104 spanned by the battery pack 1102. In thesecond variant, the battery pack can additionally or alternately bemounted to spars 1106 and/or spars 1108 and/or pinned to an uppersurface of the wing (e.g., to improve vibration characteristics).

In a first example, the battery pack 1102 and/or battery modules 1110can be packaged as fully enclosed structures with ingress and/or thermalprotections. In a second example, the battery pack and/or modules arenot fully enclosed and/or thermally protected until they are mounted(e.g., with a separate closeout covering the access hole). In the secondvariant, the battery pack is electrically incomplete before mountingand/or installation. Battery modules 1110 can be electrically connectedin series to cooperatively generate a pack voltage (e.g., after they aremounted, during mounting). Preferably, the battery modules 1110 areconnected in a manner to minimize the number of high-voltage fasteningoperations (e.g., only one fastening operation above half-pack voltage,fewer than half of fastening operations above half-pack voltage, etc.),but can be connected in any suitable manner.

FIG. 12 is a perspective view of the battery module 1110 from thebattery pack 1102 of FIG. 11 .

FIG. 13 is a cutaway plan view of an example of a wing 1100 and nacelle1302 of the rotorcraft 200 showing battery packs mounted therein. As canbe seen from the figure, nacelle battery pack 1306 comprises a number ofbattery modules 1304. The battery pack 1306 and/or battery modules 1304can be packaged as fully enclosed structures with ingress and/or thermalprotections. In a second example, the battery pack 1306 and/or batterymodules 1304 are not fully enclosed and/or thermally protected untilthey are mounted (e.g., with a separate closeout covering an accesshole). In the second variant, the battery pack 1306 is electricallyincomplete before mounting and/or installation. Battery modules 1304 canbe electrically connected in series to cooperatively generate a packvoltage (e.g., after they are mounted, during mounting). Preferably, thebattery modules 1304 are connected in a manner to minimize the number ofhigh-voltage fastening operations (e.g., only one fastening operationabove half-pack voltage, fewer than half of fastening operations abovehalf-pack voltage, etc.), but can be connected in any suitable manner.

Nacelle-mounted battery packs 1306 or battery modules 1304 can have anysuitable geometry. Preferably, a frontal cross section of thenacelle-mounted battery pack is circumscribed by the nacelle geometry,which can reduce/minimize a frontal area of the nacelle and anassociated drag influence, however the pack can alternately be optimizedto reduce the exposed (exterior) surface area of the nacelle, or beotherwise to reduce the drag influence of the nacelle. The nacellegeometry can alternately be modified to accommodate a nacelle-mountedbattery pack, and can include a circular cross section on a frontalportion of the nacelle tapering and/or lofting into a rectangular crosssection (mounting to the wing)—that can improve aerodynamic and/orpackaging efficiency. Preferably, the nacelle-mounted battery pack widthis within a threshold percentage difference of the height (e.g., for afrontal cross section, spanwise width, vertical height, etc.), which canbe within 50%, 25%, 15%, 10%, 5%, equal, and/or any other thresholddifference. The nacelle-mounted battery pack geometry can be defined bya single battery pack, a single battery module, and/or cooperativelydefined by a plurality of modules. In a specific example, anacelle-mounted battery pack volume is within a threshold difference ofa wing-mounted battery pack volume, which can be 5%, 10%, 20%, 50%,exactly equal, and/or any other suitable volume difference.

FIG. 14 is a perspective view of the battery module 1304 from thebattery pack 1306 of FIG. 13 .

FIG. 15 is a cutaway perspective view of the wing 1100 and nacelle 1302of FIG. 13 , illustrating the battery modules 1110 of battery pack 1102mounted between ribs 1104, spar 1106 and spar 1108, and battery modules1304 of battery pack 1306 mounted in nacelle 1302.

FIG. 16 is a perspective view of a battery pack 1600 and associatedmounting brackets for use in the system of FIG. 1 according to anotherexample. The battery pack 1600 is a wing-mounted battery pack for arotorcraft 200, mounted in the wing 1804 that is illustrated in moredetail in FIG. 18 . For purposes of clarity, not all structureassociated with the battery pack 1600 has been illustrated in FIG. 16 .

The battery pack 1600 is mounted to wing ribs 1806 or other fore-aftsupporting structures in the wing using a mounting bracket 1602 and amounting bracket 1604. The battery pack 1600 is rigidly mounted on oneside to mounting bracket 1602 (partially obscured in the figure), whichis in turn mounted to a rib 1806 or other fore-aft mounting structure inthe wing 210 along a lower edge 1606. Mounting bracket 1602 has the samegeneral appearance as mounting bracket 1604, with the exception thatmounting bracket 1604 provides a rigid connection (practically speaking)between the battery pack 1600 and a rib 1806 or other structure on whichthe mounting bracket 1602 is mounted, while mounting bracket 1604provides rotational movement and/or rotational compliance betweenbattery pack 1600 and mounting bracket 1604 as discussed below.

Mounting bracket 1604 includes two elongate, spaced-apart connectinglinks, which in the illustrated example take the form of hanger 1610 andhanger 1612, which are rotationally coupled to the mounting bracket 1604at an upper end and rotationally coupled to the battery pack 1600 at alower end. Mounting bracket 1604 is also mounted to a rib 1806 or otherfore-aft mounting structure in the wing 210 along a lower edge 1608. Therotational coupling between the hanger 1610/hanger 1612 and the batterypack 1600 and between the hanger 1610/hanger 1612 and the mountingbracket 1604 need not provide complete rotational freedom, as long assufficient rotation or rotational compliance is provided to permitrelative motion between the mounting brackets and battery pack asdescribed herein, without transmitting undue forces to the battery pack1600

FIG. 17A is a plan view of the right hand side mounting bracket 1604 ofFIG. 16 and FIG. 17B is a perspective view of the mounting bracket 1604of FIG. 17A. As can be seen from the figures, hanger 1612 is coupled tothe mounting bracket 1604 at an upper end by rotational coupling 1702and is coupled to a shaft 1712 at its lower end by rotational coupling1706. The shaft 1712 is in turn coupled to the battery pack 1600.Likewise, hanger 1610 is coupled to the mounting bracket 1604 at anupper end by rotational coupling 1702 and is coupled to a shaft 1714 atits lower end by rotational coupling 1708. The shaft 1714 is in turncoupled to the battery pack 1600. The rotational couplings in oneexample may be bearings, such as a sleeve or other bearing, but may beany other suitable rotational coupling.

Holes 1718 are provided in mounting bracket 1604 through which the lowerends of the hanger 1610 and hanger 1612 pass (including shaft 1712,shaft 1714 and rotational coupling 1706 and rotational coupling 1708)with sufficient clearance to allow the hanger 1610 and hanger 1612 torotate relative to mounting bracket 1604 about rotational coupling 1702and rotational coupling 1704 to a sufficient degree to accommodateflexing of the wing 1804 as discussed below.

Hanger 1610 and hanger 1612 are generally oriented vertically when therotorcraft 200 is parked and/or cruising, so that the weight of thebattery on the right side (in FIG. 16 ) is supported by tension inhanger 1610 and hanger 1612. As mentioned above, the mounting bracket1602 supporting the left side of the battery pack 1600 provides aneffectively rigid connection between the battery pack 1600 and therotorcraft 200. The mounting points on the left and right sides of thebattery pack 1600 are symmetrically positioned with respect to eachother.

Since the mounting bracket 1604 and the mounting bracket 1602 areoriented in a fore-aft direction of the wing 1804, twisting of the wing1804 will tend to cause rotation of mounting bracket 1604 with respectto mounting brackets 1602 as shown by arrows 1710 in FIG. 17A. When thisoccurs, mounting bracket 1604 will similarly rotate with respect tobattery pack 1600 without transmitting twisting forces to battery pack1600, due to rotation of hanger 1610 and hanger 1612 relative tomounting bracket 1604 that is permitted by the rotational coupling 1702,rotational coupling 1704, rotational coupling 1706 and rotationalcoupling 1708.

Similarly, bending of the wing 1804 will cause mounting bracket 1604 totip towards or away from mounting bracket 1602 as shown by arrows 1716.Due to the length and thinness (comparatively low area moment ofinertia) of the hanger 1610 and hanger 1612, they are able to bendaround the fore-aft axis of the wing, to accommodate this relativemovement of the mounting brackets, without transmitting undue forces tothe battery pack 1600. In an alternative example, the rotationalcouplings may be selected or configured to permit relative rotation ofthe mounting bracket 1604 with respect to the battery pack 1600 asindicated by arrows 1716. For example, rotational coupling 1706 androtational coupling 1708 may be ball joints in such a case.

FIG. 18 is a perspective view of part of a wing 1804 and nacelles 1802for use in the rotorcraft 200 of FIG. 2 according to another example. Ascan be seen, the wing 1804 includes a number of ribs 1806, between whichare mounted a number or battery packs 1600, as described above withreference to FIG. 17A and FIG. 17B. In this example there are twobattery packs 1600 between each pair of ribs 1806. Additional structure,such as mounting plates 1808 may be provided to permit mounting andsupport of the battery packs 1600 to or between the ribs 1806.

Also provided on an upper rear surface of the wing are a plurality ofvent outlets 1810 and burst membranes 112, one for each battery pack1600 in this example, although more or less are contemplated asdiscussed above. The vent outlets 1810 are preferably located on theupper rear surface of the wing since this positioning will direct anydischarge resulting from a thermal event involving a battery pack 1600to be directed up and away from the underside of the rotorcraft 200,where people may be located if the rotorcraft 200 is on the ground.Additionally, directing any discharge into the low pressure area aboveand to the rear of the wing 1804 will reduce the effect of the dischargeon the aerodynamic functioning of the wing 1804 in flight.

The nacelle 1802 includes a plurality of upper nacelle battery packs1814 and lower nacelle battery packs 1902 (not visible in FIG. 18 ).Also provided on the side of the nacelle 1802 are a plurality of uppervent outlets 1816 and burst membranes 1820, one for each battery pack1814, and a plurality of lower vent outlets 1818 and burst membranes1822, one for each battery pack 1902 in this example, although more orless are contemplated as discussed above. The vent outlets 1810 arepreferably located on the side of the nacelle 1802 that is away from thefuselage 212 of the rotorcraft 200 (i.e. on the outboard side of nacelle1802), so that any discharge resulting from a thermal event involving anacelle battery pack is directed away from the cabin of the rotorcraft200.

The configuration and mounting of vent outlets 1810, vent outlets 1816and vent outlets 1818 may result in an irregular surface on the wing1804 or nacelle 1802. To provide a smooth surface for drag reduction, afairing may be provided over the vent outlets. In one example, afrangible filling agent such as a filler foam or other filling compoundmay be applied to the vent outlets, which can then be finished andpainted to provide a smooth surface. Other fairing options may also beprovided such as a thin membrane or removable cover or panel.

FIG. 19 is a cross-sectional view of the nacelle of FIG. 18 . As can beseen from the figure, battery pack 1814 includes a plurality of batterymodules 104 and an enclosure 1904. The battery pack 1814 is mounted totransverse supporting structures in the nacelle 1802 by means of twomounting brackets 1916 in the same manner as the battery pack 1600 ismounted to the ribs 1806 or other supporting structures in the wing1804. Similarly, the mounting brackets 1916 serve to reduce or isolatethe battery pack 1814 from twisting or bending experienced by thenacelle 1802 as discussed above with reference to the wing in FIG. 17Aand FIG. 17B. A vent 1908 is coupled to the enclosure 1904 at one endthereof. The vent 1908 in turn is coupled to the nacelle 1802 adjacentto the nacelle skin 1912. The coupling of the vent 1908 to the nacelle1802 is a flexible coupling, which permits a degree of relative movementbetween the battery pack 1814 and the nacelles 1802 if and when thenacelle 1802 bends or twists. The flexible coupling may be formed byincluding one or more elastomeric components. In one example theflexible coupling may be a rubber expansion joint.

The enclosure 1904 serves to contain any discharge from the batterymodules 104 and direct it towards the vent 1908. Clearances between thebattery modules 104 and the enclosure 1904 and between the batterymodules 104 themselves may define pathways through which discharge mayflow, for example from the side of the battery modules 104 opposite thevent 1908 towards the vent 1908. As before, the vent 1908 at leastpartly provides a vent path 1918, normally closed by the burst membrane1820, for directing any thermal event discharges out of the nacelle1802.

Similarly, lower battery pack 1902 includes a plurality of batterymodules 104 and an enclosure 1906. The battery pack 1902 is mounted totransverse supporting structures in the nacelle 1802 by means of twomounting brackets 1914, which also serve to reduce or isolate thebattery pack 1814 from twisting or bending experienced by the nacelle1802. A vent 1910 is coupled to the enclosure 1906 at one end thereofand to the nacelle 1802 adjacent to the nacelle skin 1912. The couplingof the vent 1908 to the nacelle 1802 is a flexible coupling, whichpermits a degree of relative movement between the battery pack 1814 andthe nacelles 1802 if and when the nacelle 1802 bends or twists. Theflexible coupling may be formed by including one or more elastomericcomponents. In one example the flexible coupling may be a rubberexpansion joint.

The enclosure 1906 serves to contain any discharge from the batterymodules 104 and direct it towards the vent 1910. Clearances between thebattery modules 104 and the enclosure 1906 and between the batterymodules 104 themselves may define pathways through which discharge mayflow, for example from the side of the battery modules 104 opposite thevent 1910 towards the vent 1910. As before, the vent 1910 at leastpartly provides a vent path 1920, normally closed by the burst membrane1822, for directing any thermal event discharges out of the nacelle1802.

FIG. 20 is a perspective view of the vent shown in FIG. 19 . The vent1908 is illustrated as having a relatively larger inlet 2006 that isattached to the enclosure 1904 by means of a clamp 2004 and a relativelysmaller outlet 2002 that is coupled to the nacelle 1802

FIG. 21 is a cross-sectional view of the wing of FIG. 18 through awing-mounted battery pack 1600. As can be seen from the figure, batterypack 1600 includes one or more battery modules 104 and an enclosure2104. The battery pack 1600 is mounted to wing ribs 1806 or othertransverse supporting structures by means of two mounting brackets, suchas mounting bracket 1602 and mounting bracket 1604 described previously.Mounting bracket 1602 and mounting bracket 1604 serve to reduce orisolate the battery pack 1600 from twisting or bending experienced bythe wing 1804. A vent 2106 is coupled to the enclosure 2104 at one endthereof. The vent 2106 in turn is coupled to the wing 1804 adjacent tothe wing skin 2102. The vent 2106 is coupled to the wing 1804 using aflexible coupling 2108, which permits a degree of relative movementbetween the battery pack 1600 and the wing 1804 if and when the wing1804 bends or twists. In the illustrated example, the flexible coupling2108 comprises a first ring 2110 that is fixed to the vent 2106, asecond ring 2112 coupled to the wing 1804, and an elastomericfrustoconical portion 2114 between the first ring 2110 and second ring2112.

The enclosure 2104 serves to contain any discharge from the batterymodules 104 and direct it towards the vent 2106. Clearances betweenbattery modules 104 and the enclosure 2104 and between battery modules104 themselves may define pathways through which discharge may flow, forexample in a fore-aft direction towards the vent 2106. As before, thevent 2106 at least partly provides a vent path 2116, normally closed bythe burst membrane 1812, for directing any thermal event discharges outof the wing 1804.

FIG. 22A, FIG. 22B and FIG. 22C are schematic representations of a crosssection of a wing and an enclosed mass according to some examples. Awing 2200 may comprise a wing skin 2210 forming an upper surface 2204and a lower surface 2206. Defined in the lower surface 2206 is an accesshole 2202 through which an enclosed mass, such as battery pack 2224 maybe inserted into a cavity 2220, or through which the battery pack 2224may be accessed while in the cavity 2220. Also shown is chord line 2212,which is an imaginary straight line drawn between the leading edge andthe trailing edge of the wings 2200, in the direction of the normalairflow. The wing 2200 has a wing thickness 2208.

Wing-mounted battery packs such as battery pack 2224 can have anysuitable geometry. Preferably, the cross section of a wing-mountedbattery pack 2224 (within the cavity 2220) is optimized to reduce theside view cross sectional area to allow the pack to fit within theinternal volume of the wing, but alternately the wing and/or airfoilgeometry can be modified in order to accommodate the battery pack crosssectional geometry. Additionally or alternately, airfoil cross sectionscan be optimized to provide desirable aerodynamic characteristics (e.g.,efficient flight, high CL/CD ratio, optimized laminar to turbulentboundary transition, etc.) while packaging a wing-mounted battery packwith any suitable geometry. Preferably, the (chordwise) width ofwing-mounted battery packs is less than a distance between wing spars,but can be otherwise configured. Preferably, the battery thickness 2216thickness of wing-mounted battery packs is less than a wing thickness2208 along an entirety of the battery pack span, but can be otherwisesuitably configured. In a specific example, the battery thickness 2216is less than a minimum wing thickness 2208 of the airfoil cross sectionfor all chordwise points between the spars 2214 (or within the cavity)and/or within the span of the battery pack. Wing-mounted battery packscan have any appropriate span (e.g., half the wingspan, 20% of the wingspan, etc.), which can be the longest dimension of the battery pack, canbe a dimension of a broad face, or can have any other suitablerelationship to the pack.

Battery packs 2224 and/or battery modules 104 can be inserted into thewing/nacelle in any suitable manner. In one example, a battery chordwiselength 2218 of the battery pack 2224 can be less than the chordwiselength of the access hole 2202. In such a case, the battery pack 2224can be inserted directly into the wing 2200 from below through theaccess hole as shown in FIG. 22C, but battery packs 102 or batterymodules 104 can be inserted from any suitable direction (inboard side,outboard side, top, front, rear, etc.). Battery packs 102 or batterymodules 104 are preferably inserted after the skin is mounted to thespars/ribs, but can be inserted with any suitable timing during theassembly process. In variants, the base plane of the battery packs 102or battery modules 104 can be angled relative to the ground (around anysuitable axis): an anhedral/dihedral angle of the wing, a twisting angleof the wing, an attack angle of the wing, and/or other wing geometriescan necessitate mounting the batteries with the base plane not parallelto the ground.

Alternatively, and as discussed in more detail below, the batterychordwise length 2218 of the battery pack 2224 can be more than thechordwise length of the access hole 2202. A closeout 2222 may beprovided, which in one example comprises a baseplate 516 and a baseplateadaptor 514 as discussed above with reference to FIG. 5 .

FIG. 23A, FIG. 23B and FIG. 23C are a sequence of schematicrepresentations illustrating a method of inserting a battery pack 2306into a wing 2302 according to one example. Battery packs or modules canbe raised vertically (e.g., from below), but additionally or alternatelycan be inserted at an angle and/or rotated into position. Angledinsertion and rotating the battery pack/module into position can enableinsertion even if a dimension of the battery exceeds a dimension of theaccess hole. In a specific example, a chordwise dimension of the batterypack/module can exceed a chordwise dimension of the access hole. Thismay provide the advantage that the edge of the battery pack can thenrest on the perimeter 2310 of the access hole after assembly, providingstructural support to the battery pack.

In such a case, as illustrated in FIG. 23A, the battery pack 2306 and/orbattery module is initially tilted so that its base plane 2312 is at anangle relative to the access hole 2304 and to its final position 2308(illustrated in dashed lines). The battery pack 2306 can then beinserted at an angle upward from right to left in FIG. 23A until thebattery pack 2306 reaches the position shown in FIG. 23B, in which thefront edge (or back edge if done in reverse) of the battery pack 2306 isfurther into the wing 2302 than its final position 2308. In thisposition the back edge of the battery pack can clear the back edge ofthe access hole 2304, and the back edge (or front edge if done inreverse) can be raised until the battery pack 2306 reaches the positionshown in FIG. 23C, in which the battery pack 2306 is aligned with itsfinal position but offset horizontally therefrom. The 2306 can then bemoved horizontally into its final position 2308; that is, backwards intoits final position 2308 in the illustrated example.

FIG. 24 is a schematic representation of battery loading apparatus 2400according to one example, for inserting a battery pack 2402 into a wing2404. The battery loading apparatus 2400 in one example includes a base2406, one or more linear actuators 2408, a tilt mechanism 2410 and afixture plate 2412.

The battery loading apparatus 2400 can orient the battery pack 2402 orbattery module(s) into the appropriate mounting pose. In variants wherethe battery pack 2402 is mounted to a baseplate prior to assembly, thefixture plate 2412 can include an upper surface 2414 that is a negativeof the baseplate curvature, contour and/or retention features (edges,extruded walls, hooks, etc.) to ensure that the battery pack 2402remains secure during insertion/fastening. In variants, the fixtureplate 2412 and/or the rest of the battery loading apparatus 2400 canallow for tool and/or fastener access/clearance to enable assembly.Alternately, the fixture plate and/or battery loading apparatus 2400 canprevent tool access or block line of sight to a portion of the lowersurface of the wing 2404 and/or baseplate of the battery pack 2402(e.g., for variants utilizing adhesives or bonding agents to secure thebase plate).

The linear actuators 2408 can include actuators that can operate alongboth vertical (z-axis) and horizontal (x-y) axes to align the batterywith an access hole, raise the battery through an access hole, and movethe battery pack inside the wing 2404 as described above with referenceto FIG. 23A to FIG. 23C. The actuators comprising the linear actuators2408 can be of any type (e.g., hydraulic, pneumatic, manual,electrical), can be a compound actuators capable of movement in multipledirections or comprise one or more single direction linear actuatorslocated together or distributed around the battery loading apparatus2400. In one example, the linear actuator 2408 is only operablevertically while castor wheels are provided on the base 2406 to permithorizontal movement of the fixture plate 2412 and thus battery pack2402. In another implementations however, an x-y actuator may beprovided or the wheels may be motorized to provide horizontal movementof the battery pack 2402 relative to the wing 2404.

The tilt mechanism 2410 provides rotational alignment of the batterypack if required, for example if the battery pack 2402 is inserted intothe wing as described above with reference to FIG. 23A to FIG. 23C. Thetilt mechanism 2410 can be of any type (e.g., hydraulic, pneumatic,manual, electrical), can be capable of rotation around one or multipleaxes as required. The methods and structures described herein provideexamples of how a battery pack or battery module may be inserted into awing or nacelle. However, the battery packs and/or battery modules canotherwise be suitable inserted and/or mounted within a wing or nacelleor other part of the rotorcraft 200.

Embodiments of the system and/or method can include every combinationand permutation of the various system components and the various methodprocesses, wherein one or more instances of the method and/or processesdescribed herein can be performed asynchronously (e.g., sequentially),concurrently (e.g., in parallel), or in any other suitable order byand/or using one or more instances of the systems, elements, and/orentities described herein.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the examples of the invention disclosed herein withoutdeparting from the scope of this invention defined in the followingclaims.

What is claimed is:
 1. An aircraft, comprising: a battery pack; aninternal support structure to support the battery pack in the aircraft;and a bracket for coupling the battery pack to the support structure,the bracket including a first connecting link rotationally coupled tothe bracket at a first location and a second connecting linkrotationally coupled to the bracket at a second location, wherein thefirst connecting link is rotationally coupled to the battery pack at athird location and the second connecting link is coupled to the batterypack at a fourth location.
 2. The aircraft of claim 1, wherein thebracket is a first bracket that is coupled to a first side of thebattery pack, the aircraft further comprising: a second bracket rigidlycoupled to an opposite side of the battery pack from the first side. 3.The aircraft of claim 2, wherein the supports structure is located in awing of the aircraft and a plane of the first and second brackets arealigned with a fore-and-aft direction of the aircraft.
 4. The aircraftof claim 3, wherein the connecting links are configured to bend when thebrackets tip toward or away from each other under bending of the wing.5. The aircraft of claim 2, wherein the support structure is located ina nacelle of the aircraft and a plane of the first and second bracketsare aligned perpendicular to a fore-and-aft direction of the nacelle. 6.The aircraft of claim 1, wherein the bracket is coupled to a rib of awing of the aircraft.
 7. The aircraft of claim 1, wherein the connectinglinks are strip shaped and coupled to the bracket and the battery packat respective ends thereof.
 8. The aircraft of claim 1, wherein thefirst and second connecting links are oriented vertically.
 9. Theaircraft of claim 1, wherein the rotational couplings are bearings. 10.The aircraft of claim 1, wherein at least one of the rotationalcouplings is a ball joint.
 11. An aircraft, comprising: a battery pack;an internal support structure to support the battery pack in theaircraft; a first bracket rigidly coupling the battery pack to thesupport structure; and a second bracket rotationally coupling thebattery pack to the support structure.
 12. The aircraft of claim 11,wherein the first and second brackets are located on opposite sides ofthe battery pack.
 13. The aircraft of claim 11, wherein the internalsupport structure is located in a wing of the aircraft and the first andsecond brackets are aligned in a fore-aft direction of the aircraft. 14.The aircraft of claim 11, wherein the internal support structure islocated in a nacelle of the aircraft and the first and second bracketsare aligned along a transverse direction of the aircraft.
 15. Theaircraft of claim 11, wherein the second bracket comprises at least onehanger to support a mass of the battery pack in tension.
 16. Theaircraft of claim 15, wherein the at least one hanger is coupled to thebracket at an upper location of the hanger and to the battery pack at alower location of the hanger.
 17. The aircraft of claim 16, comprising afirst hanger coupled to the bracket at a first location and a secondhanger coupled to the bracket at a second location, the first and secondlocations being horizontally spaced apart.
 18. The aircraft of claim 17,wherein the first and second hangers are rotationally coupled to thebracket.
 19. The aircraft of claim 18, wherein the first and secondhangers are rotationally coupled to the battery pack.
 20. The aircraftof claim 19, wherein the first and second hangers are rotationallycoupled to the bracket and to the battery using bearings.